subsys: console: Add buffered output support to console subsystem

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>

include/console.h

@@ -13,16 +13,17 @@
 extern "C" {
 #endif
 
-/** @brief Initialize console_getchar() call.
+/** @brief Initialize console_getchar()/putchar() calls.
  *
  *  This function should be called once to initialize pull-style
- *  access to console via console_getchar() function. This function
- *  supersedes, and incompatible with, callback (push-style) console
- *  handling (via console_input_fn callback, etc.).
+ *  access to console via console_getchar() function and buffered
+ *  output using console_putchar() function. This function supercedes,
+ *  and incompatible with, callback (push-style) console handling
+ *  (via console_input_fn callback, etc.).
  *
  *  @return N/A
  */
-void console_getchar_init(void);
+void console_init(void);
 
 /** @brief Get next char from console input buffer.
  *
@@ -38,6 +39,15 @@ void console_getchar_init(void);
  */
 u8_t console_getchar(void);
 
+/** @brief Output a char to console (buffered).
+ *
+ *  Puts a character into console output buffer. It will be sent
+ *  to a console asynchronously, e.g. using an IRQ handler.
+ *
+ *  @return -1 on output buffer overflow, otherwise 0.
+ */
+int console_putchar(char c);
+
 /** @brief Initialize console_getline() call.
  *
  *  This function should be called once to initialize pull-style

samples/subsys/console/echo/Makefile

@@ -0,0 +1,4 @@
+BOARD ?= qemu_x86
+CONF_FILE = prj.conf
+
+include ${ZEPHYR_BASE}/Makefile.inc

samples/subsys/console/echo/prj.conf

@@ -0,0 +1,4 @@
+CONFIG_CONSOLE_PULL=y
+CONFIG_CONSOLE_GETCHAR=y
+CONFIG_CONSOLE_GETCHAR_BUFSIZE=64
+CONFIG_CONSOLE_PUTCHAR_BUFSIZE=512

samples/subsys/console/echo/src/Makefile

@@ -0,0 +1 @@
+obj-y += main.o

samples/subsys/console/echo/src/main.c

@@ -0,0 +1,16 @@
+#include <zephyr.h>
+#include <console.h>
+
+void main(void)
+{
+	console_init();
+
+	while (1) {
+		u8_t c = console_getchar();
+
+		console_putchar(c);
+		if (c == '\r') {
+			console_putchar('\n');
+		}
+	}
+}

samples/subsys/console/echo/testcase.ini

@@ -0,0 +1,8 @@
+[test]
+tags = samples
+build_only = true
+# TODO:
+# #error "Interrupt not available in uart riscv32-qemu"
+# #error "Interrupt-driven Altera JTAG UART not implemented yet"
+platform_exclude = qemu_riscv32 qemu_nios2
+filter = CONFIG_UART_CONSOLE

samples/subsys/console/getchar/src/main.c

@@ -4,7 +4,7 @@
 
 void main(void)
 {
-	console_getchar_init();
+	console_init();
 
 	while (1) {
 		u8_t c = console_getchar();

subsys/console/Kconfig

@@ -18,7 +18,7 @@ choice
 	prompt "Console 'get' function selection"
 
 config CONSOLE_GETCHAR
-	bool "Character by character input"
+	bool "Character by character input and output"
 	select UART_CONSOLE_DEBUG_SERVER_HOOKS
 	select CONSOLE_HANDLER
 
@@ -38,6 +38,15 @@ config CONSOLE_GETCHAR_BUFSIZE
 	  default is optimized to save RAM. You may need to increase
 	  it e.g. to support large host-side clipboard pastes.
 
+config CONSOLE_PUTCHAR_BUFSIZE
+	int "console_putchar() buffer size"
+	default 16
+	help
+	  Buffer size for console_putchar(). Must be power of 2. The
+	  default is optimized to save RAM. You may need to increase
+	  it e.g. to support large host-side clipboard pastes (with
+	  echo).
+
 endif # CONSOLE_GETCHAR
 
 endif # CONSOLE_PULL

subsys/console/getchar.c

@@ -7,6 +7,7 @@
 #include <zephyr.h>
 #include <uart.h>
 #include <misc/printk.h>
+#include <console.h>
 #include <drivers/console/console.h>
 #include <drivers/console/uart_console.h>
 
@@ -14,16 +15,58 @@
 #error CONFIG_CONSOLE_GETCHAR_BUFSIZE must be power of 2
 #endif
 
+#if CONFIG_CONSOLE_PUTCHAR_BUFSIZE & (CONFIG_CONSOLE_PUTCHAR_BUFSIZE - 1) != 0
+#error CONFIG_CONSOLE_PUTCHAR_BUFSIZE must be power of 2
+#endif
+
 static K_SEM_DEFINE(uart_sem, 0, UINT_MAX);
 static u8_t uart_ringbuf[CONFIG_CONSOLE_GETCHAR_BUFSIZE];
 static u8_t i_get, i_put;
 
+static K_SEM_DEFINE(tx_sem, 0, UINT_MAX);
+static u8_t tx_ringbuf[CONFIG_CONSOLE_PUTCHAR_BUFSIZE];
+static u8_t tx_get, tx_put;
+
+static struct device *uart_dev;
+
+static int console_irq_input_hook(u8_t c);
+
+static void uart_isr(struct device *dev)
+{
+	uart_irq_update(dev);
+
+	if (uart_irq_rx_ready(dev)) {
+		char c;
+
+		while (1) {
+			if (uart_fifo_read(dev, &c, 1) == 0) {
+				break;
+			}
+			console_irq_input_hook(c);
+		}
+	}
+
+	if (uart_irq_tx_ready(dev)) {
+		if (tx_get == tx_put) {
+			/* Output buffer empty, don't bother
+			 * us with tx interrupts
+			 */
+			uart_irq_tx_disable(dev);
+		} else {
+			uart_fifo_fill(dev, &tx_ringbuf[tx_get++], 1);
+			tx_get &= CONFIG_CONSOLE_PUTCHAR_BUFSIZE - 1;
+		}
+	}
+}
+
 static int console_irq_input_hook(u8_t c)
 {
 	int i_next = (i_put + 1) & (CONFIG_CONSOLE_GETCHAR_BUFSIZE - 1);
 
 	if (i_next == i_get) {
-		printk("Console buffer overflow - char dropped\n");
+		/* Try to give a clue to user that some input was lost */
+		console_putchar('~');
+		console_putchar('\n');
 		return 1;
 	}
 
@@ -34,6 +77,26 @@ static int console_irq_input_hook(u8_t c)
 	return 1;
 }
 
+int console_putchar(char c)
+{
+	unsigned int key;
+	int tx_next;
+
+	key = irq_lock();
+	tx_next = (tx_put + 1) & (CONFIG_CONSOLE_PUTCHAR_BUFSIZE - 1);
+	if (tx_next == tx_get) {
+		irq_unlock(key);
+		return -1;
+	}
+
+	tx_ringbuf[tx_put] = c;
+	tx_put = tx_next;
+
+	irq_unlock(key);
+	uart_irq_tx_enable(uart_dev);
+	return 0;
+}
+
 u8_t console_getchar(void)
 {
 	unsigned int key;
@@ -48,9 +111,9 @@ u8_t console_getchar(void)
 	return c;
 }
 
-void console_getchar_init(void)
+void console_init(void)
 {
-	uart_console_in_debug_hook_install(console_irq_input_hook);
-	/* All NULLs because we're interested only in the callback above. */
-	uart_register_input(NULL, NULL, NULL);
+	uart_dev = device_get_binding(CONFIG_UART_CONSOLE_ON_DEV_NAME);
+	uart_irq_callback_set(uart_dev, uart_isr);
+	uart_irq_rx_enable(uart_dev);
 }